Background. Ecstasy, 3,4-methylenedioxymethamphetamine (MDMA), is a synthetic compound increasingly popular as a recreational drug. Tablets known as ecstasy contain MDMA, but may also contain caffeine, ephedrine, paramethoxyamphetamine, 3,4-methylenedioxyamphetamine (MDA), amphetamine, methamphetamine, and ketamine. After absorption MDMA is metabolized to MDA, 4-hydroxy-3- metoxymetamphetamine (HMMA) and 4-hydroxy-3- metoxyamphetamine (HMA). After that HMMA and HMA are conjugated and excreted by urine. The aim of this report was to confirm by toxicological post mortem analyses of poisoned person organs that ecstasy had been the cause of his death. Case report. We reported the death of a 17-year-old boy after the ingestion of ecstasy. MDMA and metabolites were determined by multicolumn high performance liquid chromatography with UV spectral detection (HPLC-UV). Toxicological tests showed the presence of MDMA in all samples. When examining post mortem material (the organs), the highest concentrations were measured in the stomach (835,97 μg/g) and kidney (801,14 μg/g). The minimal concentration was in the liver (22,26 μg/g). Conclusion. The obtained results of MDMA and its metabolites concentrations showed abuse of a high dose of ecstasy. .